Die for manufacturing rods or wire of compounds material with non-round cross-section

ABSTRACT

A die for manufacturing rods of rectangular cross-section from a core of aluminium or an aluminium alloy and a casing of copper or a copper alloy by hydrostatic extrusion of a compound billet of such materials has a cup-shaped bottom which may be spherical, ellipsoidal, hyperbolic or parabolic in cross-section and a conical upper part. The bottom parts of the generatrices in axial section through the die form an angle which is between 120* and 180*, preferably between 150* and 170*, and a conical upper part has a cone angle between 40* and 120*.

United States Patent [191 Korsell et al.

DIE FOR MANUFACTURING RODS OR WIRE OF COMPOUNDS MATERIAL WITH NON-ROUND CROSS-SECTION Inventors: Torsten Korsell; Hans Larker; Erik Lundblad; Jan Nilsson, all of Robertsfors, Sweden Allmanna Svenska Elektriska Aktieholaget, Vasteras, Sweden Filed: Mar. 21, 1974 Appl. No.: 453,388

Assignee:

Foreign Application Priority Data Apr. 10, 1973 Sweden............................ 73050114 0.5. CI. 72/60,?2/258; 72/467 rm. c1. B21c 25/02 Field of Search 72/60, 258, 467; 29/4735, 29/475, 480, 474.3

[ June 3, 1975 [56] References Cited UNITED STATES PATENTS 3,457,760 7/1969 Cassady et al. 72/258 3,677,050 7/1972 Ahmed 72/60 3,756,054 9/1973 Nilsson 72/60 Primary Examiner-Richard J. Herbst [57] ABSTRACT 7 Claims, 4 Drawing Figures DIE FOR MANUFACTURING RODS OR WIRE OF COMPOUNDS MATERIAL WITH NON-ROUND CROSS-SECTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die for manufacturing rods or wire with a core of aluminum or an aluminum alloy and a casing of copper or a copper alloy by hydrostatic extrusion of a compound billet of aluminium and copper.

2. The Prior Art During hydrostatic extrusion a billet is enclosed in a pressure chamber with a die having an opening with the desired cross-section of the rod. The billet is surrounded by a pressure medium and is pressed out through the die opening under the action of this pressure medium when it is subjected to a pressure of such a magnitude that the material of the billet is plastically deformed. If a product composed of several materials, a compound product, is to be manufactured. a billet composed of at least two materials is the starting material. The billet then consists of a core of one or more materials and a casing of another material surrounding the core. This compound billet is provided at the rear end with sealing members preventing the pressure medium from penetrating in between the core and easing of the billet. At the front the billet is shaped so that sealing is obtained between the casing and the die. In the manufactured product the same relation is obtained between the core and the cross-section of the casing as in the billet. The shape of the die is of considerable importance for the extrusion. This is particularly the case when extruding compound products having a thin casing around a core.

The two US. Pat. Nos, 3,654,687 and 3,620,059 describe hydrostatic extrusion of compound products having a core of one material and a casing of another material. The die used in the extrusion has a conical inlet opening. During hydrostaticextrusion the cone has been very pointed in most cases, usually the cone angle has been about 45. When using dies with these pointed inlet cones good results have been obtained when extruding homogeneous materials, and it has been possible to carry out the extrusion at relatively low pressures. When extruding compound profiles of, for example, aluminium and copper, normally dies with a relatively pointed inlet cone have been used earlier. Usually the cone angle has been between 35 and 60. In some case a die with a pointed inlet cone and a blunter bottom cone has been tested.

Profiles with non-round cross-section. especially with rectangular cross-section where the ratio between width and thickness is great, are difficult to extrude. The thickness of the casing will be greater at the short sides of the sections than at its long sides. It will be thinnest in the middle of the long sides and the material in the core may break through the casing. It has been found that the geometry of the die has very great influence on the extrusion result. especially for profiles having rectangular cross-section.

SUMMARY OF THE INVENTION According to the invention a billet of one or more materials is extruded in a die with a cup-shaped bottom. Such a bottom shape makes it possible to manufacture rectangular copper-aluminium profiles with much greater widththickness thickness ratio or with less content of copper than when using previously known shapes of the die. When extruding copperaluminum profiles. a high extrusion ratio is necessary to obtain a satisfactory bond between the materials. It is desirable that the extrusion ratio be greater than 20, preferably greater than 50.

The transition between the cup-shaped bottom of the die and the die opening is of extremely great impor tance. At this transition the angle between the tangents to the bottom generatrices should be between l20 and 180 in an axial section through the centre of the die and perpendicular to the longest side of the die opening. The complete inner part of the die can be cupshaped with a spherical, ellipsoidal, hyperbolic or parabolic shape (that is, shapes formed by revolution of a conic section), but it is suitable to make the die with a conical part which changes into a cup-shaped part.

When extruding rectangular profiles only this shape of the die has given a satisfactory result in series production with a ratio between width and thickness exceeding 10:1. Profiles with a cross-section of X 6 with a copper content of 15% have been manufactured in a commercial production plant.

The method and the die according to the invention give extremely good extrusion results. This is especially the case when extruding compound products with a thin casing, particularly when extruding profiles having an aluminum core and a thin copper casing.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described more closely with reference to the accompanying drawings, in which:

FIG. I shows schematically a section through a pressure chamber during the hydrostatic extrusion of a billet inserted in the chamber;

FIG. 2 on a larger scale a view of the die from the inlet side; and

FIGS. 3 and 4 section through the die at A-A and C-C, respectively, in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings show a press table 1 and a pressuregenerating piston 2 which is arranged in a hydraulic press, the rest of which is not shown, in which there is a cylinder for the operation of the piston 2. The pressure chamber comprises a high-pressure cylinder 3 which is constructed from a steel cylinder 4, a strip sheath 5 of rectangular tape material of great tensile strength wound on under pre-stressing and end pieces 6. Between the end pieces 6 and a spacing sleeve 7 arranged in the cylinder there are arranged gaskets 8 and 9 which constitute seals between the cylinder 4 and the extrusion die 10 and the piston 2, respectively. In the pressure chamber is a billet 11 consisting of a core 12 of aluminium or an aluminium alloy and a surrounding casing of copper or a copper alloy. At the inner end of the billet there is an annular slot 14 in the core, in which there is a ring 15 preventing the pressure medium 16 from penetrating in between the core and the casing. In this way the surfaces are held free from contamination and a high pressure force is obtained between the core and the casing, which results in a good connection. The connection can be further improved by providing the core I2 with another slot 18. An extruded strip is designated at 17.

1n FIGS. 2 4. K designates a conical portion and S a cup-shaped portion of an inlet opening 20 in the die 10. In the figures. a cup-shaped bottom S with a spherical shape is shown. which is simplest form the manufac turing point of view. The die opening 21 is rectangular with sides equal to B and H. FIG. 3 shows an axial section through the center of the die and perpendicular to the longitudinal axis of the die opening 2|. In this section the angle between the tangent T to the generatrix G at the transition between the cup-shaped portion S and the die opening 21 is equal to 2 a. This angle should be between 120 and 180, preferably 150 and 170. The cone angle of the conical inlet portion K is 2 B. This angle should be between 40 and 120'. By giving the cup-shaped bottom S of the inlet opening 20 an ellipsoidal shape it is possible to choose the angle 20: between the tangents T so that it is equal in all sections perpendicular to the sides of the die opening or in all sections through the center of the die.

Test results illustrate the importance of the shape of the die. Below are shown the results of the extrusion of a copper-aluminum bar having a width of 75 mm and a thickness of 6 mm and with a copper casing, the cross-section of which is of the whole crosssection of the profile. The extrusion ratio is 50.

Test 1 The die had an inlet cone with a top angle of 80 which changes into a substantially spherical bottom. The angle between the tangent to the bottom generatrices at the center of the long sides of the die opening was 160. A faultless product was obtained.

Test 11 A die of the same kind as in Test 1 was used, except that the angle between the said tangents was 140. The copper layer of the product had small perforations of aluminum in the middle of the broad sides of the profile.

Test 111 A die of the same kind as in Test 1 was used, except that the angle between the said tangents was 180. The copper layer of the product had regulart perforations of aluminum at the thin sides of the profile.

When extruding profiles with greater contents of copper or with a smaller numerical value of the ratio between width and thickness of the profile. a satisfactory product within a greater angular range is obtained.

We claim:

1. Die for manufacturing rods with a core of aluminium or an aluminium alloys and a casing of copper or a copper alloy by hydrostatic extrusion of a compound billet having an inlet portion having an outer part and a cup-shaped bottom part and a die opening in the bottom part having longer and shorter sides, the tangents to the generatrices to the bottom part forming a continuously increasing angle from the outer part to the die opening, the tangents to the bottom part of the generatrices in axial section through the die perpendicular to the longest side of the die opening. forming an angle (2 a which is between and 180, the outer part of the die being a conical part which merges into the cupshaped bottom part.

2. Die according to claim 1, in which (2 a is between and 3. Die according to claim 1, in which the tangents to the bottom parts of the generatrices in axial section through the die perpendicular to shorter sides of the die opening form an angle (2 a which is between 120 and 4. Die according to claim 3, in which (2 a is between 150 and 170.

5. Die according to claim 1, in which the cup-shaped bottom part of the die has the shape formed by revolution of a conic section.

6. Die according to claim 1, in which the outer conical part has a cone angle (2 B between 40 and 120.

7. A method which comprises hydrostatically extruding a billet with a core of aluminium or an aluminium alloy and a casing of copper or a copper alloy through a die having an inlet portion having an outer part and a cup-shaped bottom part and a die opening in the bottom part having longer and shorter sides, the tangents to the generatrices to the bottom part forming a continuously increasing angle from the outer part to the die opening. the tangents to the bottom parts of the generatrices in axial section through the die perpendicular to the longest side of the die opening, forming an angle (2 a which is between 120 and 180, the outer part of the die being a conical part which merges into the cupshaped bottom part. 

1. DIE FOR MANUFACTURING RODS WITH A CORE OF ALUMINUM OR AN ALUMINUM ALLOYS AND A CASING OF COPPER OR A COPPER ALLOY BY HYDROSTATIC EXTRUSION OF A COMPOUND BILLET HAVING AN INLET PORTION HAVING AN OUTER PART AND A CUP-SHAPED BOTTOM PART AND A DIE OPENING IN THE BOTTOM PART HAVING LONGER AND SHORTER SIDES, THE TANGENTS TO THE GENERATRICES TO THE BOTTOM PART FORMING A CONTINUOSULY INCREASING ANGLE FROM THE OUTER PART TO THE DIE OPENING, THE TANGENTS TO THE BOTTOM PART OF THE GENERATRICES IN AXIAL SECTION THROUGH THE DIE PERPENDICULAR TO THE LONGEST SIDE OF THE DIE OPENING, FORMING AN ANGLE (2A) WHICH IS BETWEEN 120* AND 180*, THE OUTER PART OF THE DIE BEING A CONICAL PART WHICH MERGES INTO THE CUP-SHAPED BOTTOM PART.
 1. Die for manufacturing rods with a core of aluminium or an aluminium alloys and a casing of copper or a copper alloy by hydrostatic extrusion of a compound billet having an inlet portion having an outer part and a cup-shaped bottom part and a die opening in the bottom part having longer and shorter sides, the tangents to the generatrices to the bottom part forming a continuously increasing angle from the outer part to the die opening, the tangents to the bottom part of the generatrices in axial section through the die perpendicular to the longest side of the die opening, forming an angle (2 Alpha ) which is between 120* and 180*, the outer part of the die being a conical part which merges into the cup-shaped bottom part.
 2. Die according to claim 1, in which (2 Alpha ) is between 150* and 170*.
 3. Die according to claim 1, in which the tangents to the bottom parts of the generatrices in axial section through the die perpendicular to shorter sides of the die opening form an angle (2 Alpha ) which is between 120* and 180*.
 4. Die according to claim 3, in which (2 Alpha ) is between 150* and 170*.
 5. Die according to claim 1, in which the cup-shaped bottom part of the die has the shape formed by revolution of a conic section.
 6. Die according to claim 1, in which the outer conical part has a cone angle (2 Beta ) between 40* and 120*. 